we were at CTI 2 years ago, and a coupple we met there traded places with CSS every other day - They liked the AN beach better than the Island. Based on that, it should not be a problem how often you go!

They will probably let you go twice if they have room. If you have already been once, they won't deny someone else a spot for you, but they allow 10 couples per trip. As long as you ask them nicely you should get to go more that once.